colourblind, that is your affair. There is then a defect in your organ of apprehension; but that does not interfere with the physical reality, which we know from better equipped observers. This doctrine of the; open door, as I may call it, or of the window with degrees of transparence, through which reality comes to you as it is, though with varying completeness, is very powerful in twentieth century realism, and is at times connected, strangely enough, with some extreme doctrines of other worlds.
It follows—and this is largely the point of the doctrine—that the physical reality which is the object of mind is the thing, or part of the thing, which you suppose yourself to apprehend. I mean, it is in no sense part of your own body or mind. Your organs let it in, but they do not, in principle, modify it, except in degree. [The question of error can, I think, be dealt with from this position, in agreement with the best thinkers, at least if we read "real" for "physical." Error is always about a reality.] Your mind, then,
